Oxidation PAG 5.3

Cards (23)

  • partial oxidation - distillation
  • complete oxidation - reflux
  • distillation diagram
  • distillation - most volatile components distil out first
  • water should flow against gravity to help remove air from the condenser for more efficient cooling
  • why is a condenser used?

    to cool and condense the vapour into liquid
  • why are anti-bumping beads used?
    to reduce the pressure within the system
  • why is there no thermometer when heating under reflux?
    to avoid pressure building + not heating to specific temp as its continuous
  • reflux is a continuous process of evaporation followed by condensation where volatile components cannot escape
  • why is a heating mantle used?

    even and controlled heat source which prevents plastic components melting away
  • oxidising agent: [O]
  • reagent: acidified potassium dichromate (VI) - K2Cr2O7/H2SO4 OR Cr2O7 2- / H+
  • explanation of OMG:
    • oxidation number is +6
    • then chromium is reduced, gaining electrons
    • then chromium's charge changes from +6 to +3 and this is green
  • why is gentle heating used?
    primary alcohol can be partially oxidised to form an aldehyde
  • primary alcohol
  • distillation
  • water is formed when aldehyde forms
  • heat under reflux - complete oxidation
  • oxidation of aldehyde: aldehyde is refluxed with acidifies K2Cr2O7 to form carboxylic acid
  • oxidation to secondary alcohols: easily oxidised to ketones by heating under reflux.
  • oxidation of tertiary alcohol: not oxidised under normal conditions, but do break down with vigorous oxidation, so it remains orange
  • for oxidation to take place, two H atoms must be on adjacent C and O atoms
  • reducing agent: [H]